Information retrieval technology is widely used in web search engines. One information retrieval technology generally employed is inverted indexing, in which a list of the documents that contain any supported word is maintained in a data structure (index table) in association with that word. Then, when processing a search term, the inverted index is used to speed up the retrieval process by accessing the inverted index table with that term to locate the documents that contain that term.
However, when the data scale is large enough, scanning the index table is still time consuming. For example, consider attempting to retrieve relevant content from tens of millions of documents in a rapid time, such as thirty milliseconds. Conventional inverted indexing is not capable of meeting such retrieval demands.